Method of removing film deposits



Sept. 13, 1966 D. c. WOOD METHOD OF REMOVING FILM DEPOSITS OriginalFiled Jan. 6, 1961 INVENTOR.

BY ja m www, v /w United States Patent 3,272,652 METHOD OF REMOVING FILMDEPOSITS Donald C. Wood, Fredonia, Wis., assignor to WhirlpoolCorporation, a corporation of Delaware Original application Jan. 6,1961, Ser. No. 81,083.

Divided and this application Nov. 12, 1964, Ser.

4 Claims. (Cl. 134-34) This application is a division of my copendingapplication Ser. No. 81,083, filed Jan. 6, 1961, now abandoned.

This invention relates to dishawashers and in particular to a method ofremoving film deposits from the washed objects.

A serious problem in the use of automatic dishwashers is the developmentof a cloudy film on glassware, dishes and the like as a result ofwashing such articles a number of times in hard water. This film appearsto comprise a calcium or magnesium complex, the deposit of which may beaccelerated by washing such articles as in detergents containingphosphates or silicates.

The present invention is concerned with the removal of this film fromthe glassware and comprehends the removal thereof by contacting theglassware with a fluid containing monovalent electropositive ions.

A principal feature of the invention is, therefore, the provision of anew and improved method of removing film deposits on elements such asglassware resulting from the washing thereof.

Another feature of the invention is the provision of such a method ofremoving film deposits including the steps of providing a solutioncontaining monovalent electropositive metal ions and contacting saidsolution with said deposits on the elements.

A further feature of the invention is the provision of such a method ofremoving film deposits wherein the solution comprises a brine solution.

Still another feature of the invention is the provision of such a methodof removing film deposits wherein the solution is formed substantiallyconcurrently with the contacting thereof with said film deposits.

Other features and advantages of the invention will be apparent from thefollowing description taken in connection with the accompanying drawingwherein:

The figure is an isometric left rear view of a dishwashing apparatusprovided with means embodying the invention for removing film depositsfrom elements such as glassware.

In the exemplary embodiment of the invention, as disclosed in thedrawing, a dishwasher generally designated of generally conventionalconstruction includes a cabinet portion 11 in which elements such asdishes and glassware may be washed. Access to the interior of thecabinet for insertion and removal of the dishes and glassware may be hadby means of a conventional cover 12 secured to the cabinet by suitablehinge structures 13. Washing water is delivered to the interior of thecabinet by suitable conventional means such as a control valve 14connected to a conduit 15 which is, in turn, connected to a suitablesupply of hot water (not shown). Valve 14 may comprise a conventionalsolenoid operated valve which, when opened, passes the hot water througha discharge conduit 16 to an inlet means 17 for delivering the water tothe interior of the cabinet through a suitable spray device 18 therein.The wash water is recirculated within the cabinet by suitableconventional means including a drain 19 and a pump 20. Suitable controlmeans including a timer (not shown) may be associated with the valve 14to effect an automatic operation of the dishwasher as desired.

The present invention comprehends the provision of means for introducinginto the dishwasher or generating 3,272,652 Patented Sept. 13, 1966therein a fluid adapted to remove film deposits on glassware and thelike resulting from the washing thereof. If has been found that thesedeposits which produce a cloudy, unsightly film on the glassware arecaused primarily by orthosilicates and/or orthophosphates in the washingsolutions in hard water. These deposits may be removed by placing theglassware in a solution containing monovalent electropositive ions for asubstantial period of time whereby the glassware is restored tosparkling clarity. As shown in the drawing, the contacting of such afluid with the glassware may be eflected in dishwasher 10 by providing aselector valve 21 in the conduit 16 selectively operable to direct theincoming water through a bypass conduit 22 leading toa container 23 inwhich a suitable quantity, such as two pounds, of salt per each 20pounds of Water is placed. A discharge conduit 24 leads from thecontainer 23 to the inlet means 17 whereby water delivered throughconduit 22 and passed through the container 23 to form a salt solutionis delivered through the conduit 24 and inlet means 17 to the interiorof the dishwasher to be sprayed and circulated therein similar to thewashing water. The spraying and circulation of the salt solution may becontrolled by a suitable timer control 25 so that this operation iscontinued for a predetermined period of time such as 1 /2 hours toassure that the film deposit on the glassware is fully removed. The timenecessary to fully remove the deposit has been found to vary with theamount of deposit on the glassware and the strength of the salt solutionand, thus, timer 25 may be provided with suitable adjusting means 26 forvarying the length of the cycle. In the conventional dishwasher, aquantity of approximately two pounds of salt provides an approximate 10%salt solution; satisfactory film removal may be effected withsubstantially less salt such as a quantity providing as low asapproximately 3% solution. Where a mini mum treatment time is desired,the solution may be a saturated solution. The customary spray action ofthe dishwasher accelerates the ion exchange to remove the deposit in arelatively short time.

The removal of the film deposits from the glassware may be effectedrelatively infrequently, depending on the rate of deposit of the film.Thus, control 25 may be provided with a manually operable push button 27for effecting the film removing operation only when desired. Thus,selector valve 21 may be normally maintained in the position whereinflow of the water from valve 14 is through conduit 16. Upon operation ofthe control 25 to initiate the film removing cycle, the control mayactuate the valve 21 to direct the water to conduit 22 rather thanconduit 16. The control may be arranged so that upon completion of thecontrol cycle the valve 21 is restored to the normal position fordirecting the water from the valve 14 to conduit 16 allowing normaldishwashing operation until the operator once again desired to effect afilm removing operation.

The salt which may be used for removing the film deposits may compriseany salt providing monovalent electropositive ions such as metal orhydrogen ions. Illustratively, sodium chloride may be utilized. To flushthe dishwasher and rinse the glassware subsequent to the film removingoperation, the control 25 may be arranged to provide an additional rinsecycle.

If desired, the salt may be dispensed directly into the dishwasher froma dispenser such as the well known types for dispensing detergent but ofincreased size to accommodate the amount of salt required.

This invention may be practiced either periodically as described or morefrequently as, for example, in each cycle of dishwashing. By adding abrine and rinse operation to an otherwise conventional dishwashing cyclefollowing its wash and rinse operations, the objectionable deposits maybe effectively prevented from building up on the articles.

Having described my invention as related to the emmodiment shown in theaccompanying drawing, it is my intention that the invention be notlimited by any of the details of description, unless otherwisespecified, but rather be construed broadly within its spirit and scopeas set out in the accompanying claims.

The embodiment of the invention in which an exclusive property orprivilege is claimed is defined as follows:

1. The method of removing film on tableware deposited thereon as aresult of washing the tableware with phosphate or silicate containingdetergents in hard water, comprising the steps of:

forcibly spraying the tableware with a solution of hard water and atleast approximately 3% by weight sodium chloride to dissolve thedeposited film; and

rinsing the tableware with water to remove said solution and dissolvedfilm.

2. The method of claim 1 wherein the water utilized in each of the filmremoving and rinsing steps is provided from a common source.

3. The method of claim 1 wherein said film removing solution is asaturated solution.

4 4. The method of claim 1 wherein the spraying and rinsing steps areconducted within a chamber and wherein the sodium chloride is introducedinto the chamber for dissolving in hard water therein to form said filmremoving solution.

References Cited by the Examiner UNITED STATES PATENTS 1,870,318 8/1932Stoddard 13429 2,008,839 7/1935 Samson 134-22 2,395,260 2/1946 Farmer eta1 13422 X 2,424,049 7/1947 Parker et a1 l3428 X 2,766,151 10/1956Stearns 134-27 2,825,666 3/1958 Stoddard 13428 2,884,349 4/1959 Axelrad134-22 FOREIGN PATENTS 118,498 5/1944 Australia. 647,673 12/ 1950 GreatBritain.

MORRIS O. WOLK, Primary Examiner.

J. ZATARGA, Assistant Examiner.

